Boiler drum



Jan. 25, 1938. T. yw. BIGGER ET AL BOILER DRUM Filed l July 22, 193e Patented Jan. 25, 1938 UNITED STATES BOILER DRUM Trafford W. Bigger and Frank L.l Hargrova Schenectady, N. Y., assignors to General Electric Company, a corporation of New York Application July z2, 1936, serial No. 91,946.

1 Claim.

ments. The liquid is discharged from such heating elements into a drum at reduced pressure whereby it is at least partly converted into vapor,

the vapor being discharged from the drum to a consumer and the remaining liquid being recirculated through the heating elements.

The object, of the invention ,is to providel an improved construction of boiler drums of the type above specified to attain a better separation of liquid from vapor. Complete separation of liquid v2() particles from the vapor to be discharged from the drum is important, especially in connection with boilers such as mercury boilers using operating liquids other than water because liquid particles entrained in the vapor are injurious when impinging on machine elements, for instance the blading of a mercury vapor turbine.

For a consideration of what we believe to be novel and our invention, attention is directed to the following description and the claim appended thereto in connection with the accompanying drawing.'

In the drawing, Fig. 1 represents a front view of a mercury boiler drum embodying our invention; Fig. 2 is a. section along the line 2-2 of Fig. l; and Fig. 3 is a section alongthe line 3 3 oi Fig. 2.-

The mercury boiler drum comprises an outer body having an upper portion or dome Ill, an intermediate cylindrical portion Il and a lower i0 portion I2. The upper portion I0 is larger in diameter than the intermediate portion Il, whereas the.lower portion I2 is considerably smaller in diameter-than the intermediate portion. In the present example the lower portion has a diameter of the order of about one-half of the diameter of the intermediate portion II and the lower end of the lower portion I2, is tapered'. downward, ending in a conduit connection I3 from which liquid is discharged from the drum and conducted to a heating element, not shown.

The small diameterand the tapering of the lower portion. I2, reduce the liquid space therein to a minimum. This is desirable in mercury boilers due to the high cost of mercury. ',A- definite liquid level is normally maintained in the lower portion I2. To this end it is connected to chambersv I4 and I5 formingparts of a level-indicating device, not shown, the level being normallyl maintained at a point intermediate the connections to the Achambers I4 and. I5. 'Ihe dome I0 is se- 5 cured to the intermediate portion Il by a weld I6, and the intermediate portion Il and the -lower portion I2 are united by .another w'eld I1. The dome Il). has a central opening closed by means of a ring I8 secured to the dome by a weld 10 I3 and a cylinder member 28 disposed within the ring I8 and secured thereto at its upper end by a weld 2|. The cylinder20 has a flanged bottom 22 engaging the lower end of the sleeve I8. This arrangement permits access to the interior of the 15 drum for the purpose of inspection after removal of the weld 2| and lowering of the cylinder member 20. e During lowering, the cylinder member 20 may be held by means including a handle 23 secured to the interior of the member 20. The .p20 liquid to be converted into vapor is conducted to the drum by means of two conduits 24 and 25 connected to diametrically opposite points of the dome. The liquid thus conducted to the dome is received by an annular inlet chamber 23 hav- `25 ing an outerwall formed by two curved sheets or Walls 21 and 28 secured to the drum by welds 23 and 30 respectively. Thev chamber 26 has an inner cylindrical wall 3l connected to the' outer wall 21, 28 by a top 32 and a bottom 33. The v30 bottom 33 includes an annular row of partitions 34 forming a plurality of nozzles 35 through which liquid'is discharged from the chamber 26 into the space deiined by the intermediate drum portion II. VThe conduits 24, 25 discharge tan- 35 gentially towards the inner surfaces of the curved sheets 21 and 28 so that the liquid discharged from the conduits assumes at once a circular path within the chamber 26. The outer edges of the partitions 34 are spaced from the inner 40 surfaces of the curved walls 21 and 28 of the inlet chamber 26 to form a continuousspace 34a for receiving liquid from the inlet conduits 24 and 25 and for facilitating distribution of theliquid to the nozzles 35. The body oi' liquid contained in 45 said space 34a also acts as a cushion-to absorb some of the impact energy of theliquid entering' the chamber through the inlet conduits 24 and 25. The liquid .is discharged from the chamber 28, as stated above, through the row of nozzles 50 35 which are arranged so as to cause tle'liquidv 'to follow a helical path downward alongthe inner surface of the intermediate portion I I. The

length of the helical path ispreferably a multiple of 360l angular degrees.- The-'liquid is at least 5 5 partly evaporated on its path through the intermediate portion I I. The greater inertia of the liquid and the action of centrifugal force acting thereon cause the liquid to form a spinning cylindrical sheath or boundary layer on the surface of the intermediate portion II. thereby forcing the vapor inward, that is, towards the central portion of the space within the intermediate drum portion I I, whence the vapor is discharged in the direction of the arrows 36a through the opening 36 defined by the inner surface ci the wall 3|. The vapor is conducted to a consumer, not shown, by a conduit 31 secured to the dome IIJ by a weld 3B and communicating with a space within the dome through an opening 39 in an upper end. portion of the conduit 31. Liquid particles remaining entrained in the vapor are substantially removed in the dome I0 as such particles impinge on the surface of the drum. This liquid is collected within grooves 40 and 4I defined between the wall of the drum and the curved sheets 21 and 2t. These grooves communicate with the lower drum portion I2 by conduits 42 and 43 respectively. The provision of a separate path for conducting liquid from the dome III to the lower drum portion I2 is important in that it prevents liquid once separated from the vapor in the dome from againvbecoming mixed with the vapor. To this end, ring member 3l has an upper projection 44 so that any liquid dropping onto the top of the chamber 26 is prevented from flowing into the opening 36 and becoming entrained in the vapor flowing therethrough. To the same end, the flanged bottom 22 of the cylinder member 20 is provided with a cone-shaped surface 5. Liquid particles entrained in the vapor and impinging the surface 45 are deflected laterally to be collected in the grooves 40 and 4I.

In order to permit proper level control in the lower portion I2 it is desirable to maintain a quiet liquid pool therein. Such quiet pool also assures proper level-indication. This is accomplished in accordance with our invention by the provision of means for destroying the velocity energy of the liquid in the lower space of the intermediate drum portion II and directing the liquid in a smooth.. gentle path into the lower drum portion I2. These means form a zig-zag path for the liquid and as' shown in the present instance comprise three rows of blades 46, 41, and 46. The last row of blades 4I is disposed within the upper end of the lower drum portion I2 which upper end projects into the lower end of the intermediate drum portion II. 'I'he inner edges of the blades 4l are secured to a pipe 49 which acts asV a stiifener for the blades and also as a vent, permitting vapor to be conducted from the lower drum portion I2 to the intermediate drum portion I I. The second row of blades 41 is disposed between the outer surface of the extension-of the lower drumv portion I2 and the inner surface of a cylindrical element 5l. The first row of blades 46 is located between the outer surface of the cylindrical element 6l and the .inner surface of the intermediate drum portion II. The upper portions II of the first row of blades 46 are bent in the direction of-fiow of liquid. as indicated by arrows l2, to reduce the impact of the liquid on the blade portions 5I.

The lower portions of the blades 46 are vertical. Thus, the first row of blades changes the spiral paths of the liquid into a vertical, downwardly directed path. The blades 41 and 48 are -vertically arranged to further straighten and quiet the flow so that liquid discharged from the lower ends between the blades 46 is forced upward in a vertical path defined between the blades 41, whence it is discharged therefrom to flow downwardthrough the vertical passages defined between adjacent blades 48. Thus, the three rows of blades form a zig-zag path through which the liquid flows on its passage from the intermediate drum to the pool in the lower drum portion I2. The zig-zag path is of considerable length and thereby straightens and quiets the flow of the liquid, causing the liquid to flow gently into the poolwithin the lower drum portion I2 without causing therein substantial disturbances of the level. The lower drum portion I2 is also connected to a conduit 53 through which liquid may be conducted to the drum, for instance, from a mercury condenser, not shown.

Having described the method of operation of our invention, together with the apparatus which we now consider to represent the best embodiment thereof, we desire to have it understood that the apparatus shown is only illustrative and that the invention may be'carried out by other means.

What we claim as new and desire to secure by Letters Patent of the United States is:

A boiler drum including the combination of a cylindrically lshaped vertically disposed drum having an upper portion, an intermediate portion and a lower portion, the diameter of the intermediate portion being smaller than that of the upper but considerably larger than that of the lower portion, an annular chamber formed within and supported on the upper portion, conduit means for conducting heated liquid to the chamber, the chamber having a bottom with a ring of nozzles for discharging uid into the intermediate portion and for causing the fluid to flow in a helical path along the surface of the intermediate portion whereby the liquid by the action of centrifugal force is forced outward forming a layer on the surface of the intermediate portion and causing the vapor to be forced radially inward, means including a vapor discharge conduit connected to the upper drum portion and a central opening formed by the annular chamber for conducting vapor from the intermediate portion through the upper portion to a consumer, means disposed in the lower end of the intermediate portion and including an extension of the lower portion projecting into the intermediate portion and a plurality of rows of blades for directing the liquid in a vertical path into the lower portion, and means for conducting liquid particles separated from the vapor in the upper portion into the lower portion comprising grooves formed between the chamber and the wall of the upper portion and conduits between the grooves and the lower portion.

TRAFFORD W. BIGGER.

FRANK L. HARGROV'E. 

